JAG wrote:Returning to the point in question, what could the KM have achieved had it decided to stick to Diesel and commerce warfare in 1934?

The powerplant would be heavier and occupy a larger volume while also needing a very long and thin ship (the P-class cruisers come to mind) in order to get the best posible speed out of the engines, everything else, weapons and armor would take a second seat to the powerplant needs in weight and volume....

So maybe a Bismarck-heavy ship, longer and thinner (30m maybe?), with 2x4x35/38cm in order to fit (and save weight) 16x12MZu42/58 large diesels on 4 shafts for 144.000hp? With triple 15cm superfiring over the main turrets achieving the same 6x15cm broadside as IRL.

Hopefully 30kts might be achieved with a huge range.

Feasible?

Hull has to carry fuel as well as motors armor etc. diesels use half as much fuel than turbine propulsion....so the heavier diesels are not a problem. Bismarck has 7000t fuel plus 3000t turbine/boilers. The same power with diesel might be 5000 t motors but it would have. ...5000t diesel fuel. The OPQ class was estimated @ 3nm/t diesel , while H class was estimated @ 2.2 nm/t diesel. Bismarck would be something in-between...may be 2.5nm/t diesel. This suggests an endurance of ~ 13,000nm @ 19knots or 5000nm @ 28 knots.

JAG wrote:Returning to the point in question, what could the KM have achieved had it decided to stick to Diesel and commerce warfare in 1934?

The powerplant would be heavier and occupy a larger volume while also needing a very long and thin ship (the P-class cruisers come to mind) in order to get the best posible speed out of the engines, everything else, weapons and armor would take a second seat to the powerplant needs in weight and volume....

So maybe a Bismarck-heavy ship, longer and thinner (30m maybe?), with 2x4x35/38cm in order to fit (and save weight) 16x12MZu42/58 large diesels on 4 shafts for 144.000hp? With triple 15cm superfiring over the main turrets achieving the same 6x15cm broadside as IRL.

Hopefully 30kts might be achieved with a huge range.

Feasible?

Hull has to carry fuel as well as motors armor etc. diesels use half as much fuel than turbine propulsion....so the heavier diesels are not a problem. Bismarck has 7000t-7700 fuel plus 3000t turbine/boilers. The same power with diesel might be 5000 t motors but it would have. ...5000- 5700t diesel fuel. The OPQ class was estimated @ 3nm/t diesel , while H class was estimated @ 2.2 nm/t diesel. Bismarck would be something in-between...may be 2.5nm/t diesel. This suggests an endurance of ~ 13,000-14,800nm @ 19knots or ~ 5800-6600nm @ 28 knots.... that's 50% more endurance for 3/4 of the bunkerage.

Sorry for the delay it has been a crazy week and somehow this fell through the cracks.

Thanks for the sim, I was thinking that we could even go further and simply downgrade the main battery to 35cm guns as was considered at one point, maybe we can squeeze a couple knots that way. Would you mind reassessing with that modification?

OK getting speed up to 31 knots DEEP was difficult as well as keep propulsion weights close and strength/sea keeping average. Shifting to 15" guns maybe well impossible...and keep to same protection /diesel speed and displacement parameters.

I think this would have been a better use of tonnage than either Scharnhorst or Bismarck, it may not have the staying power, but it does have a decent speed (31kts and better when light) and the good range necessary for a raider.

It just needs to hope not to run into Richelieu!

Oh, and I meant 15cm, for the secondaries, not 15in.

Re the 35cm gun, it was used, just not at sea, the Mackensen guns were used on land, and in WW2 its development would actually have had a head start over the 38cm since it was originally intended to replace the 28cm in the twins with them.

30m was the beam of the Scharnhorst and its TDS had a depth of 5m IIRC plus unused space due to the hasty redesign of the ships to take a smaller powerplant.

Steve Crandell wrote:So planning to develop an entirely new 14" gun, a caliber never before used by the German Navy.

Also, reducing the beam also reduces the effectiveness of the TDS.

This is a common misunderstanding. the 15" gun was started in 1934 by Krupp along with the 16" gun and the 11"C34 gun. However at that moment the only orders from the KM were for a dozen 11"C28 guns for the Panzerschiffe D & E. The follow on Panzerschiffe armament was either to be triple 33cm turrets or twin 35cm guns..there was no 15" gun turrets ordered at that time and anyway Hitler interfered with the whole process forcing the KM to alter designs back to the 11"gun turrets, to placate the British.